A measuring device and method for contact resistance

Abstract

The present application provides a measuring device and a measuring method for contact resistance, which are used to measure the contact resistance of electrodes of a flow battery. The device includes a first type of battery and a second type of battery. The first electrode and the second electrode have the same first thickness, and the third electrode has a second thickness. The first electrode has the same first contact area with the first bipolar plate and the second bipolar plate respectively. The second electrode has the same second contact area with the second bipolar plate and the third bipolar plate respectively. The third electrode has the same third contact area with the fourth bipolar plate and the fifth bipolar plate respectively. An electrolyte is provided inside the first electrode, the second electrode, and the third electrode. During the measurement process, it is not necessary to ignore certain resistance values to cause measurement errors. It belongs to in-situ measurement, considering the influence of the liquid-phase circuit and the electrolyte on the contact resistance. It is beneficial to reduce the measurement difficulty and operation complexity of the contact resistance and improve the measurement accuracy of the contact resistance.

Description

Technical Field

[0001] This application mainly relates to the field of flow batteries, and particularly to a measuring device and a measuring method for contact resistance. Background Art

[0002] Contact resistance refers to the resistance between two conductors at the contact point or on the contact surface. The existence of contact resistance will affect the efficiency of electron flow between the two conductors, thereby affecting the performance of the circuit. In a flow battery, there is a contact surface between the bipolar plate and the electrode, and contact resistance exists on the contact surface. The energy industry standard of our country (NB / T 42007-2013) discloses "A Test Method for Bipolar Plates for All-Vanadium Flow Batteries", but this method ignores the contact resistance between carbon felts, and the carbon felts are not tested in an electrolyte environment, and no electrode system is formed, which belongs to off-site measurement, making the measurement result inaccurate and the measurement result on the small side.

[0003] Therefore, there is an urgent need for a measuring device and a measuring method for contact resistance with accurate measurement results, fast operation and in-situ measurement. Summary of the Invention

[0004] In view of the technical problems of inaccurate measurement results and off-site measurement of contact resistance, this application provides a measuring device and a measuring method for contact resistance.

[0005] To solve the above technical problems, this application provides a measuring device for contact resistance, which is used to measure the contact resistance of the electrodes of a flow battery, and includes a first type of battery and a second type of battery. Among them, the first type of battery includes a first bipolar plate, a second bipolar plate, a third bipolar plate, a first electrode and a second electrode. The first electrode is arranged between the first bipolar plate and the second bipolar plate, and the second electrode is arranged between the second bipolar plate and the third bipolar plate; the second type of battery includes a fourth bipolar plate, a fifth bipolar plate and a third electrode, and the third electrode is arranged between the fourth bipolar plate and the fifth bipolar plate; among them, the first electrode and the second electrode have the same first thickness, the third electrode has a second thickness, and the first thickness is different from the second thickness; the first electrode has the same first contact area with the first bipolar plate and the second bipolar plate respectively, the second electrode has the same second contact area with the second bipolar plate and the third bipolar plate respectively, the third electrode has the same third contact area with the fourth bipolar plate and the fifth bipolar plate respectively, and moreover, the first contact area, the second contact area and the third contact area are all the same; electrolytes are arranged inside the first electrode, the second electrode and the third electrode.

[0006] In some embodiments, the first type of battery and the second type of battery are arranged independently of each other, and the third bipolar plate and the fourth bipolar plate are two independent bipolar plates; or, the first type of battery and the second type of battery are integrally arranged, wherein the third bipolar plate and the fourth bipolar plate are the same bipolar plate.

[0007] In some embodiments, the measuring device further includes a seal and a pole frame, and the seal and the pole frame are used to seal the first type of battery and the second type of battery.

[0008] In some embodiments, the measuring device further includes an electrochemical workstation for measuring the resistance of the first type of battery and the second type of battery.

[0009] In some embodiments, the first bipolar plate, the second bipolar plate, the third bipolar plate, the fourth bipolar plate, and the fifth bipolar plate are respectively provided with connectors for connecting to a plurality of wires, and the wires are used to connect to the electrochemical workstation.

[0010] To solve the above technical problems, the present application further provides a method for measuring contact resistance, which is applied to the measuring device as described above. The measuring method includes:

[0011] Measuring a first resistance R1 of a circuit formed by the first bipolar plate, the second bipolar plate, and the first electrode therebetween; in the resistance test, the electrode generally refers to an electrode system including a solid-phase electrode and a liquid-phase electrolyte, and the electrode resistance is the electrode system resistance.

[0012] Measuring a second resistance R2 of a circuit formed by the fourth bipolar plate, the fifth bipolar plate, and the second electrode therebetween;

[0013] Measuring a third resistance R3, where the third resistance R3 is the equivalent resistance of a circuit formed by connecting in parallel a circuit formed by the first bipolar plate and the first electrode in series and a circuit formed by the third bipolar plate and the second electrode in series, and then connecting in series with the second bipolar plate.

[0014] In some embodiments, the electrochemical workstation is used to measure the first resistance R1, the second resistance R2, and the third resistance R3 according to the alternating current impedance method.

[0015] In some embodiments, the step of measuring the first resistance R1 of the circuit formed by the first bipolar plate, the second bipolar plate, and the first electrode therebetween includes: connecting one of the positive or negative electrodes of the electrochemical workstation to the first bipolar plate, and connecting the other of the positive or negative electrodes to the second bipolar plate.

[0016] In some embodiments, the first resistance R1 is calculated using the following formula: 2R b +R e +2R c ; where R b represents the resistance value of any one of the first bipolar plate, the second bipolar plate, the third bipolar plate, the fourth bipolar plate, and the fifth bipolar plate; R e represents the resistance of the first electrode or the second electrode, and R c represents the contact resistance between any one electrode and the corresponding bipolar plate.

[0017] In some embodiments, the step of measuring the second resistance R2 of the circuit formed by the fourth bipolar plate and the fifth bipolar plate and the second electrode therebetween comprises: connecting one of the positive electrode or the negative electrode of the electrochemical workstation to the fourth bipolar plate, and connecting the other of the positive electrode or the negative electrode to the fifth bipolar plate.

[0018] In some embodiments, the second resistor R2 is calculated using the following formula: 2R b +KR e +2R c Among them, KR e is the resistance of the third electrode, and K represents the ratio of the second thickness to the first thickness.

[0019] In some embodiments, the third resistor R3 is measured, and the third resistor R3 is the equivalent resistance of a circuit formed by connecting the first bipolar plate and the first electrode in series, and a circuit formed by connecting the third bipolar plate and the second electrode in series in parallel, and then connecting the second bipolar plate in series. The step of measuring the third resistor R3 includes: connecting one of the positive electrode or the negative electrode of the electrochemical workstation to the first bipolar plate and the third bipolar plate, and connecting the other of the positive electrode or the negative electrode to the second bipolar plate.

[0020] In some embodiments, the third resistor R3 is calculated using the following formula: b +(R b +R e +2R c ) / 2.

[0021] In some embodiments, the contact resistance is calculated by combining R1, R2, and R3.

[0022] Compared with the prior art, the present application has the following advantages: there is no need to separate the bipolar plate and the electrode during the measurement process, and there is no need to ignore certain resistance values to cause large measurement errors; the measuring device contains electrolyte, forming a complete electrode system, and is an in-situ measurement, taking into account the influence of the liquid phase circuit and the electrolyte on the contact resistance. This is conducive to reducing the measurement difficulty and operation complexity of the contact resistance and improving the measurement accuracy of the contact resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The accompanying drawings are included to provide a further understanding of the present application. They are included and constitute a part of the present application. The accompanying drawings illustrate embodiments of the present application and together with the present specification serve to explain the principles of the present application. In the accompanying drawings:

[0024] Figure 1 is a schematic diagram of a measuring device provided in an embodiment of the present application.

[0025] Figure 2 is another schematic diagram of a measuring device provided by an embodiment of the present application.

[0026] Figure 3 is a flowchart of a measurement method provided by an embodiment of the present application.

[0027] Reference numerals

[0028] First type of battery, 100;

[0029] First bipolar plate, 101;

[0030] Second bipolar plate, 102;

[0031] Third bipolar plate, 103;

[0032] First electrode, 104;

[0033] Second electrode, 105;

[0034] First contact surface, 106;

[0035] Second contact surface, 107;

[0036] Second type of battery, 200;

[0037] Fourth bipolar plate, 201;

[0038] Fifth bipolar plate, 202;

[0039] Third electrode, 203;

[0040] Third contact surface, 204;

[0041] Seal, 300. Detailed implementation manners

[0042] To more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the accompanying drawings required for the description of the embodiments. Obviously, the accompanying drawings in the following description are only some examples or embodiments of the present application. For those of ordinary skill in the art, without creative efforts, the present application can also be applied to other similar scenarios based on these drawings. Unless obvious from the language context or otherwise stated, the same reference numerals in the figures represent the same structure or operation.

[0043] As shown in the present application, unless the context clearly indicates an exceptional situation, words such as "a", "an", "one", and / or "the" are not specifically singular and may also include plural. Generally speaking, the terms "include" and "comprise" only indicate the inclusion of the clearly identified steps and elements, and these steps and elements do not constitute an exclusive list. The method or device may also include other steps or elements.

[0044] Unless otherwise specifically stated, the relative arrangements of components and steps, numerical expressions, and numerical values set forth in these embodiments do not limit the scope of the present application. At the same time, it should be understood that, for the sake of convenience of description, the dimensions of the various parts shown in the drawings are not drawn in actual proportional relationships. Technologies, methods, and devices known to those of ordinary skill in the relevant art may not be discussed in detail, but where appropriate, the said technologies, methods, and devices should be regarded as part of the description. In all the examples shown and discussed herein, any specific values should be construed as merely exemplary and not as a limitation. Therefore, other examples of the exemplary embodiments may have different values. It should be noted that like reference numerals and letters denote like items in the following drawings, and thus, once an item is defined in one drawing, it need not be further discussed in subsequent drawings.

[0045] In the description of the present application, it should be understood that the orientation or positional relationships indicated by orientation words such as "front, rear, upper, lower, left, right", "lateral, vertical, perpendicular, horizontal", and "top, bottom" are generally based on the orientation or positional relationships shown in the drawings, and are only for the convenience of describing the present application and simplifying the description. Without contrary description, these orientation words do not indicate and imply that the devices or elements referred to must have a specific orientation or be constructed and operated in a specific orientation, and thus should not be construed as limiting the scope of protection of the present application; the orientation words "inside, outside" refer to the inside and outside relative to the contours of the respective components.

[0046] In addition, it should be noted that the use of terms such as "first", "second", etc. to limit components is only for the convenience of distinguishing the corresponding components. Without otherwise stating, the above terms have no special meanings, and thus should not be construed as limiting the scope of protection of the present application. In addition, although the terms used in the present application are selected from well-known and commonly used terms, some of the terms mentioned in the description of the present application may be selected by the applicant according to his or her judgment, and their detailed meanings are described in the relevant parts of the description herein. In addition, it is required to understand the present application not only through the actual terms used, but also through the meanings implied by each term.

[0047] Flowcharts are used in the present application to illustrate the operations performed by the systems according to the embodiments of the present application. It should be understood that the operations before or below do not necessarily have to be performed precisely in sequence. On the contrary, they can be performed in reverse order or simultaneously. At the same time, other operations may be added to these processes, or one or several steps may be removed from these processes.

[0048] The present application provides a measuring device for contact resistance, which is used to measure the contact resistance of electrodes of a flow battery. The present application does not limit the type of flow battery, and it can be applicable to all-vanadium flow batteries, iron-chromium flow batteries, zinc-bromine flow batteries, etc. The examples described in the present application are to measure the contact resistance between a bipolar plate and an electrode. In fact, the measuring device of the present application can also be used to measure the contact resistance between an electrode and other flow battery components, which is not limited herein.

[0049] As Figure 1 shown, a measuring device for contact resistance provided by the present application includes a first type of battery 100 and a second type of battery 200. Among them, the first type of battery 100 includes a first bipolar plate 101, a second bipolar plate 102, a third bipolar plate 103, a first electrode 104, and a second electrode 105. The first electrode 104 is disposed between the first bipolar plate 101 and the second bipolar plate 102, and the second electrode 105 is disposed between the second bipolar plate 102 and the third bipolar plate 103; the second type of battery 200 includes a fourth bipolar plate 201, a fifth bipolar plate 202, and a third electrode 203. The third electrode 203 is disposed between the fourth bipolar plate 201 and the fifth bipolar plate 202; wherein, the first electrode 104 and the second electrode 105 have the same first thickness, the third electrode 203 has a second thickness, and the first thickness is different from the second thickness; the first electrode 104 respectively has the same two first contact surfaces 106 with the first bipolar plate 101 and the second bipolar plate 102. The first contact surface 106 has a first contact area. The second electrode 105 respectively has the same two second contact surfaces 107 with the second bipolar plate 102 and the third bipolar plate 103. The second contact surface 107 has a second contact area. The third electrode 203 respectively has the same two third contact surfaces 204 with the fourth bipolar plate 201 and the fifth bipolar plate 202. The third contact surface 204 has a third contact area. The first contact area, the second contact area, and the third contact area are all the same; electrolytes are disposed inside the first electrode 104, the second electrode 105, and the third electrode 203.

[0050] In some embodiments, the first type of battery 100 and the second type of battery 200 refer to any electrode structure of the negative electrode structure or the positive electrode structure in the liquid flow battery. For example, the first type of battery 100 and the second type of battery 200 can be the positive electrode structure or the negative electrode structure of the all-vanadium liquid flow battery, and the positive electrode structure or the negative electrode structure of the iron-chromium liquid flow battery. The present application does not limit the type of electrolyte, and the electrolyte can be a substance that can conduct electricity in a solution in a broad sense. The electrolyte can also be a liquid containing +5-valent or +4-valent vanadium ions of the positive electrode of the all-vanadium liquid flow battery, or a liquid containing +3-valent or +2-valent vanadium ions of the negative electrode of the all-vanadium liquid flow battery, and examples are not given one by one here. Setting the electrolyte can obtain the actual contact resistance of the bipolar plate and the electrode under the influence of the electrolyte. The present application does not limit the material and shape of the bipolar plate. The first type of battery 100 and the second type of battery 200 can use bipolar plates of the same specifications, such as bipolar plates of the same material and shape, to ensure that the resistance of each bipolar plate is the same. This application does not limit the materials of the first electrode 104, the second electrode 105 and the third electrode 203. The electrodes can be metal electrode materials, carbon electrode materials and composite material electrodes. The electrodes of the same specifications (such as the same material) are used to ensure that their conductivity is the same, which is convenient for subsequent measurement. The first electrode 104 and the second electrode 105 have the same first thickness, and the third electrode 203 has a second thickness. The first thickness is different from the second thickness and is in a certain proportional relationship. The first thickness and the second thickness in a proportional relationship make the resistance of the first electrode 104 and the resistance of the third electrode 203 also have a certain proportional relationship, which is convenient for the subsequent simultaneous equations to solve the contact resistance. The proportional relationship will be explained in the subsequent content. The contact resistance is related to the contact area and pressure between the bipolar plate and the electrode. In order to facilitate measurement, the first contact area, the second contact area and the third contact area are the same. When the first contact area, the second contact area and the third contact area are the same and the pressure is the same, the first electrode 104, the second electrode 105 and the third electrode 203 are respectively formed with the corresponding bipolar plate. The contact resistance is the same. In this embodiment, the first type battery 100 and the second type battery 200 are independently arranged, and without the action of a wire, the two cannot be electrically connected. Among them, the third bipolar plate 103 and the fourth bipolar plate 201 are two independent bipolar plates.

[0051] like Figure 2 As shown, in some embodiments, the first type of battery 100 and the second type of battery 200 are integrally arranged. Since the bipolar plate is conductive, the first type of battery 100 and the second type of battery 200 can be electrically connected without the action of a wire. The third bipolar plate 103 and the fourth bipolar plate 201 are the same bipolar plate. The two settings of the first type of battery 100 and the second type of battery 200 do not affect the measurement results. Providing multiple settings can flexibly apply the device to different usage scenarios, thereby improving the applicability of the device.

[0052] In some embodiments, such as Figure 1 shown, the measuring device further includes a seal 300 and a pole frame (not shown in the figure). The seal 300 and the pole frame are used to seal the first type of battery 100 and the second type of battery 200 to prevent the leakage of the electrolyte. The pole frame can also provide structural support for the batteries. The seal 300 and the pole frame generally do not have electrical conductivity, so they will not affect the measurement results of the device.

[0053] In some embodiments, the measuring device further includes an electrochemical workstation (not shown in the figure), which is used to measure the resistance of the first type of battery 100 and the second type of battery 200. How to measure the resistance of the first type of battery 100 and the second type of battery 200 will be described in the following content.

[0054] In some embodiments, the first bipolar plate 101, the second bipolar plate 102, the third bipolar plate 103, the fourth bipolar plate 201, and the fifth bipolar plate 202 are respectively provided with connectors (not shown in the figure), which are used to connect to a plurality of wires, and the wires are used to connect to the electrochemical workstation. Setting connectors on the bipolar plates facilitates electrical connection and is conducive to improving the simplicity of measurement. The connectors can be fan-shaped or circular, and the specific shape of the connectors is not limited in the embodiments.

[0055] This application also provides a method for measuring contact resistance, which is applied to a measuring device such as Figure 1 - Figure 2 as described above. As Figure 3 shown, the measuring method includes:

[0056] S100. Measure the first resistance R1 of the circuit formed by the first bipolar plate 101, the second bipolar plate 102, and the first electrode 104 therebetween.

[0057] S200. Measure the second resistance R2 of the circuit formed by the fourth bipolar plate 201, the fifth bipolar plate 202, and the second electrode 105 therebetween.

[0058] S300. Measure the third resistance R3. The third resistance R3 is the equivalent resistance of the circuit formed by connecting in parallel the circuit formed by the series connection of the first bipolar plate 101 and the first electrode 104 and the circuit formed by the series connection of the third bipolar plate 103 and the second electrode 105, and then connecting in series with the second bipolar plate 102.

[0059] In some embodiments, an electrochemical workstation is used to measure the first resistor R1, the second resistor R2, and the third resistor R3 according to the alternating current impedance method. The alternating current impedance method is a non-destructive test method that can provide information on the dynamic process of the electrode interface and is thus applicable to the measurement method of contact resistance in this application. The test principle of the alternating current impedance method is that by changing the frequency of the electrical signal, the corresponding impedance value (divided into the real part and the imaginary part) can be obtained. Through the image of the real part and the imaginary part of its impedance (the battery test image can generally be approximated as a combination of a semicircle and a straight line, and the ohmic value is the real part value corresponding to when the imaginary part is zero, that is, the left endpoint of the semicircle), the ohmic value can be split and obtained. In practical applications, the ohmic value can be directly obtained through the corresponding application software. In some embodiments, the voltage range output by the electrochemical workstation can be 1 - 10 mV, and the voltage frequency can be 0.1 - 100 kHz.

[0060] In some embodiments, the step S100 further includes: S101, connecting one of the positive or negative electrodes of the electrochemical workstation to the first bipolar plate 101, and connecting the other of the positive or negative electrodes to the second bipolar plate 102. In the measurement method of this application, the polarities of the first type of battery 100 and the second type of battery 200 are not distinguished, so the bipolar plate of the first type of battery 100 can be connected to any electrode of the electrochemical workstation. When the first bipolar plate 101 and the second bipolar plate 102 are connected to the electrochemical workstation and the measurement starts, the resistance between the first bipolar plate 101 and the second bipolar plate 102 includes: the resistance of the first bipolar plate 101, the contact resistance between the first bipolar plate 101 and the first electrode 104, the resistance of the first electrode 104, the contact resistance between the first electrode 104 and the second bipolar plate 102, and the resistance of the second bipolar plate 102. From the perspective of the equivalent circuit, the current passes through the first bipolar plate 101, the contact resistance between the first bipolar plate 101 and the first electrode 104, the first electrode 104, the contact resistance between the first electrode 104 and the second bipolar plate 102, and the second bipolar plate 102 in sequence, and each part is in a series relationship. According to the series rule of resistors, by summing the resistance values of each part of R1, R1 can be obtained.

[0061] In some embodiments, let the resistance value of the first bipolar plate 101 be R b , the resistance value of the first electrode 104 be R e , and the contact resistance between the first bipolar plate 101 and the first electrode 104 be R c , then the resistance value of R1 can be expressed as: R1 = 2R b + R e + 2R c .

[0062] As described above, the bipolar plates used in the first type of battery 100 and the second type of battery 200 have the same specifications. Therefore, it can be considered that the resistance values of the first bipolar plate 101, the second bipolar plate 102, the third bipolar plate 103, the fourth bipolar plate 201, and the fifth bipolar plate 202 are the same. Here, R is also used b to represent the resistance value of any one of the first bipolar plate 101, the second bipolar plate 102, the third bipolar plate 103, the fourth bipolar plate 201, and the fifth bipolar plate 202. Also, since the contact areas formed by the first bipolar plate 101, the second bipolar plate 102, the third bipolar plate 103, the fourth bipolar plate 201, and the fifth bipolar plate 202 with the corresponding electrodes are the same, the resistance values of the contact resistances are the same. Here, R is used c to represent the contact resistance between any one electrode and the corresponding bipolar plate. Since the materials, thicknesses, and areas of the first electrode 104 and the second electrode 105 are the same, here R is used e to represent the resistance values of the first electrode 104 and the second electrode 105. The difference between the third electrode 203 and the first electrode 104 and the second electrode 105 is that the second thickness of the third electrode 203 is in a proportional relationship with the first thickness of the first electrode 104 and the second electrode 105. Then, the resistance of the third electrode 203 can be expressed as KR e , where K is the ratio of the second thickness to the first thickness. The value of K can take any value, such as 2, 3, 4, and 0.5, etc., but the value of K cannot be equal to 1.

[0063] It should be noted that the first type of battery and the second type of battery have electrolytes. Therefore, the electrodes in this application generally refer to an electrode system including a solid-phase electrode and a liquid-phase electrolyte, and the electrode resistance is the electrode system resistance.

[0064] In some embodiments, step S200 further includes: step S201, connecting one of the positive electrode or the negative electrode of the electrochemical workstation to the fourth bipolar plate 201, and connecting the other of the positive electrode or the negative electrode to the fifth bipolar plate 202.

[0065] In some embodiments, the third bipolar plate 103 and the fourth bipolar plate 201 can be the same bipolar plate. Therefore, step S200 further includes S202, connecting one of the positive electrode or the negative electrode of the electrochemical workstation to the third bipolar plate 103, and connecting the other of the positive electrode or the negative electrode to the fifth bipolar plate 202.

[0066] In some embodiments, the following formula is used to calculate the second resistance R2, R2 = 2R b + KR e + 2R cFrom the perspective of the equivalent circuit, the current sequentially passes through the fourth bipolar plate 201, the contact resistance between the fourth bipolar plate 201 and the third electrode 203, the third electrode 203, the contact resistance between the third electrode 203 and the fifth bipolar plate 202, and the fifth bipolar plate 202, and each part is in a series relationship. According to the series rule of resistance, R2 can be obtained by summing the resistance values of each part of R2.

[0067] In some embodiments, step S300 also includes S301, connecting one of the positive or negative electrodes of the electrochemical workstation to the first bipolar plate 101 and the third bipolar plate 103, and connecting the other of the positive or negative electrodes to the second bipolar plate 102. From the perspective of the equivalent circuit, the current flows through two parts at the same time. The first part includes: the first bipolar plate 101, the contact resistance between the first bipolar plate 101 and the first electrode 104, the first electrode 104 and the contact resistance between the first electrode 104 and the second bipolar plate 102. The second part includes: the third bipolar plate 103, the contact resistance between the third bipolar plate 103 and the second electrode 105, the second electrode 105, the second electrode 105 and the second bipolar plate 102. The first part and the second part are parallel structures. According to the parallel law of resistance, the resistance generated by the first part and the second part in parallel is half of the first part. After the current flows through the first part and the second part at the same time, it flows through the second bipolar plate 102, and after the first part and the second part are connected in parallel, they are connected in series with the second bipolar plate 102. That is, the third resistor R3 is the equivalent resistance of the circuit formed by the first bipolar plate 101 and the first electrode 104 in series, and the circuit formed by the third bipolar plate 103 and the second electrode 105 in series, and then connected in parallel with the circuit formed by the second bipolar plate 102 in series. Therefore, in some embodiments, R3 can be expressed as: R3 = R b +(R b +R e +2R c ) / 2.

[0068] In some embodiments, since only R b , R e and R c The values of the three unknowns, R1, R2 and R3, can be measured by the electrochemical workstation. By combining the three equations, R can be obtained by solving the three-variable linear equation. b , R e and R c The result obtained by combining the above equations is: R e =(R2-R1) / (K-1), R b =2R3-R1, R c =(R1-2R b -R e ) / 2.

[0069] The measuring device provided by this application does not require the separation of the bipolar plate and the electrode during the measurement process, and does not need to ignore certain resistance values to cause large measurement errors. The measuring device contains an electrolyte and constitutes a complete electrode system, belonging to in-situ measurement, considering the influence of the liquid-phase circuit and the electrolyte on the contact resistance. It is beneficial to reduce the measurement difficulty and operation complexity of the contact resistance and improve the measurement accuracy of the contact resistance.

[0070] The following provides a test example and a comparative example in an experimental process to illustrate the actual effects of this application.

[0071] During the experimental process, the test example selects electrodes with a size of 2 cm * 2 cm, a compression ratio of 35%, a pressure of 0.1 Mpa, a porosity of 0.92 after compression, the thickness of the first electrode 104 and the second electrode 105 are both 1.7 mm after compression, the thickness of the third electrode 203 is 3.4 mm after compression, and the K value is 2. The electrolyte used for testing is a vanadium sulfate electrolyte, with an average vanadium valence state of 3.5 and a concentration of 1.7 mol / L.

[0072] The electrochemical workstation test shows that: R1 = 17.4 mΩ; R2 = 21.6 mΩ; R3 = 10.3 mΩ. By calculation, Rb = 2R3 - R1 = 2 * 10.3 - 17.4 = 3.2 mΩ; Re = (R2 - R1) / (K - 1) = (21.6 - 17.4) / (2 - 1) = 4.2 mΩ; Rc = (R1 - 2R b -R e ) / 2 = (17.4 - 2 * 3.2 - 4.2) / 2 = 3.4 mΩ. The contact resistance R c *A = 3.4 * 4 = 13.6 mΩ * cm 2 .

[0073] The comparative example uses the measurement method described in NB / T 42007-2013 mentioned in the background technology and conducts tests under the test conditions of the test example of this application. When the pressure is 0.1 MPa, the measured contact resistance R c is 10.2 mΩ·cm 2 .

[0074] From the results of the test example and the comparative example, it can be seen that under the same measurement conditions, the measurement results achieved by this application are more accurate.

[0075] The basic concepts have been described above. Obviously, for those skilled in the art, the above application disclosure is only an example and does not constitute a limitation to this application. Although not explicitly stated here, those skilled in the art may make various modifications, improvements, and corrections to this application. Such modifications, improvements, and corrections are proposed in this application, so such modifications, improvements, and corrections still belong to the spirit and scope of the exemplary embodiments of this application.

[0076] Meanwhile, this application uses specific terms to describe the embodiments of this application. For example, "an embodiment", "one embodiment", and / or "some embodiments" mean a certain feature, structure, or characteristic related to at least one embodiment of this application. Therefore, it should be emphasized and noted that the "one embodiment" or "an embodiment" or "an alternative embodiment" mentioned twice or more at different positions in this specification does not necessarily refer to the same embodiment. In addition, certain features, structures, or characteristics in one or more embodiments of this application can be appropriately combined.

[0077] Similarly, it should be noted that, in order to simplify the description of this application and thus help the understanding of one or more embodiments of the invention, in the previous description of the embodiments of this application, sometimes multiple features are grouped into one embodiment, drawing, or description thereof. However, this disclosure method does not mean that the features required by the object of this application are more than the mentioned features. In fact, the features of the embodiment are less than all the features of the single embodiment disclosed above.

[0078] In some embodiments, numbers describing the components and the quantity of attributes are used. It should be understood that such numbers used for the description of embodiments are modified by the modifiers "about", "approximately", or "substantially" in some examples. Unless otherwise stated, "about", "approximately", or "substantially" indicate that the said numbers allow a variation of ±20%. Accordingly, in some embodiments, the numerical parameters used in this application are all approximate values, and these approximate values can be changed according to the characteristics required by individual embodiments. In some embodiments, the numerical parameters should consider the specified significant digits and adopt the method of retaining the general number of digits. Although the numerical ranges and parameters used to confirm the breadth of the scope in some embodiments of this application are approximate values, in specific embodiments, the setting of such numerical values is as precise as possible within the feasible range.

Claims

1. A measuring device for contact resistance, which is used to measure the contact resistance of the electrodes of a flow battery, and is characterized in that Including a first type of battery and a second type of battery, wherein, The first type of battery includes a first bipolar plate, a second bipolar plate, a third bipolar plate, a first electrode and a second electrode. The first electrode is disposed between the first bipolar plate and the second bipolar plate, and the second electrode is disposed between the second bipolar plate and the third bipolar plate; The second type of battery includes a fourth bipolar plate, a fifth bipolar plate and a third electrode. The third electrode is disposed between the fourth bipolar plate and the fifth bipolar plate; Wherein, the first electrode and the second electrode have the same first thickness, the third electrode has a second thickness, and the first thickness is different from the second thickness; The first electrode has the same first contact area with the first bipolar plate and the second bipolar plate respectively, the second electrode has the same second contact area with the second bipolar plate and the third bipolar plate respectively, and the third electrode has the same third contact area with the fourth bipolar plate and the fifth bipolar plate respectively. Moreover, the first contact area, the second contact area and the third contact area are all the same; An electrolyte is disposed inside the first electrode, the second electrode and the third electrode; An electrochemical workstation for measuring the resistance of the first type of battery and the second type of battery.

2. The measuring device according to claim 1, characterized in that The first type of battery and the second type of battery are independently disposed, and the third bipolar plate and the fourth bipolar plate are two independent bipolar plates; or, the first type of battery and the second type of battery are integrally disposed, wherein the third bipolar plate and the fourth bipolar plate are the same bipolar plate.

3. The measuring device according to claim 1 or 2, characterized in that, Also included are a seal and a pole frame for sealing the first type of battery and the second type of battery.

4. The measuring device according to claim 1, characterized in that, The first bipolar plate, the second bipolar plate, the third bipolar plate, the fourth bipolar plate and the fifth bipolar plate are respectively provided with connectors for connecting to a plurality of wires, and the wires are used for connecting to the electrochemical workstation.

5. A method for measuring contact resistance, which is applied to the measuring device according to any one of claims 1-4, characterized in that, The measurement method includes: Measuring a first resistance R1 of a circuit formed by the first bipolar plate, the second bipolar plate and the first electrode therebetween; Measuring a second resistance R2 of a circuit formed by the second electrode between the fourth bipolar plate and the fifth bipolar plate; Measuring a third resistance R3, where the third resistance R3 is the equivalent resistance of a circuit formed by the series connection of the first bipolar plate and the first electrode, and the series connection of the third bipolar plate and the second electrode, and then in parallel, and then in series with the second bipolar plate; Solving the equations of R1, R2 and R3 to calculate the value of the contact resistance; Wherein, the resistances of the first bipolar plate, the second bipolar plate, the third bipolar plate, the fourth bipolar plate and the fifth bipolar plate are the same; The first resistor R1 is calculated using the following formula: 2R b +R e +2R c ; Among them, R b represents the resistance value of any one of the first bipolar plate, the second bipolar plate, the third bipolar plate, the fourth bipolar plate, and the fifth bipolar plate; R e represents the resistance of the first electrode or the second electrode R c represents the contact resistance between any electrode and the corresponding bipolar plate; The second resistor R2 is calculated using the following formula: 2R b +KR e +2R c ; Among them, KR e is the resistance of the third electrode, and K represents the ratio of the second thickness to the first thickness; The third resistor R3 is calculated using the following formula: R b +(R b +R e +2R c ) / 2。 6. The measuring method according to claim 5, wherein Using the electrochemical workstation to measure the first resistance R1, the second resistance R2 and the third resistance R3 according to the alternating current impedance method.

7. The measurement method according to claim 6, characterized in that, The step of measuring the first resistance R1 of the circuit formed by the first bipolar plate, the second bipolar plate and the first electrode therebetween includes: Connect one of the positive or negative electrodes of the electrochemical workstation to the first bipolar plate, and connect the other of the positive or negative electrodes to the second bipolar plate.

8. The measurement method according to claim 7, wherein The step of measuring the second resistance R2 of the circuit formed by the second electrode between the fourth bipolar plate and the fifth bipolar plate includes: Connect one of the positive or negative electrodes of the electrochemical workstation to the fourth bipolar plate, and connect the other of the positive or negative electrodes to the fifth bipolar plate.

9. The measurement method according to claim 8, wherein, The step of measuring the third resistance R3 includes: Connect one of the positive or negative electrodes of the electrochemical workstation to the first bipolar plate and the third bipolar plate, and connect the other of the positive or negative electrodes to the second bipolar plate.

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